Lowest budget air sealing solution for OSB seams – labor immaterial
Hi. I am in Zone 4a (Nashville area)
What are the very cheapest (material) solutions for air sealing OSB, that work excellent, even if more labor is involved. My labor is free, my billfold is thin.
I am building a workshop that will not be inspected; however, I want excellent air sealing.
I read Martin’s tape test articles. The Siga Wigluv is king with OSB, but I am looking at $700+ in tape if I go that route, unless it is cheaper by the case somewhere.
I got to thinking that perhaps a liquid applied sausage gun caulk or some other technology might be a good solution??
I also am thinking that I could make the air sealing layer the 2″ polyiso on the exterior, but I recall reading that it is best at the OSB level??
Anyways, thank you for your advice.
-Mike
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Replies
Something that the premium sealing tapes have in common is the acrylic adhesive. I'm not sure you need to look beyond that. As you have found 4" Wigluv runs about 78¢/ft. Zip tape seems to be the cheapest 4" tape at 30¢/ft. For an off label solution you might consider aluminium foil tape meant for sealing ductwork. Nashua 324a tape is 3" wide and 4.8 mils thick. It has acrylic adhesive that is rated down to -10° F. It sells for 9¢/ft. Nashua 330 Extreme Weather 3" tape sells for 14¢/ft. It is 3.5 mils thick but works down to -20°. While Wigluv and Zip tapes must be rolled, aluminum tape can be burnished with a rounded edge block of wood. This applies greater pressure with less work.
The various fluid applied flashings have STPe (Silyl-Terminated Polyether) polymer in common. Zip Liquid Flash sells for $29 for a 20 oz. sausage. I saw Prosoco R Guard for $23.57. The least expensive seems to be Henry Air Block for $15.65.
I think using fluid applied flashing would be more expensive and time consuming than tape. However they can be used in conjunction with tape for sealing penetrations and tricky bits. I used fluid applied for the bottoms of window openings and a few inches up the sides as well as the upper corners. Then Zip tape for the straight runs. This avoids the hassle of taping inside corners and precludes the use of expensive Zip Stretch Tape.
I sealed all seams with acoustical sealant then covered with 3m 3015/8067. A tube of acoustical sealant is cheap. I paid (Newfoundland, Canada) 2.90 cad for mulch acoustik which covers about 45’. The tape was 28 cad/75’. At a cost of about 0.45 cad/Lin foot that’s the cheapest option I could find locally. Did all the labor myself for. I’m guessing you may be able to find those materials for a cheaper cost in Nashville.
Like Martin and others, I’ve found that Zip tape sticks tenaciously to commodity OSB. It is available on the shelf at the big box stores, even if the Zip sheathing is not. And the Zip roller tool works great, and was also stocked at the big box store. Convenience, price, and performance - check.
Thank you gents.
Thrifttrust, can you explain more about the HVAC foil tape? Is this the same adhesive that is used on these air sealing tapes? Is there any expansion/contraction going on in OSB that would cause them to fail? I lLOVE the price point; but, I don't want the proverb: "cheaper is more expensive" to become my reality. If it will work, count me in!!! Budget is my middle and last name. :)
Otherwise, I am leaning towards David,'s advice of 3M tape (8067) if I can use the 2" (don't know why not). If I need 4" wide it is more economical to use ZIP tape.
I will use thrifttrusts advice of using liquid applied on window sills to avoid the serious cost of stretchable sill.
Thrifttrust, can you explain the use of acoustical sealant? I cannot understand its place in the assembly. Is it squeezed on top of seem and flattened like a fluid applied, or is it placed on top&bottom plates as well as studs where seems will land, and OSB is fastened to the acoustical beaded wood sandwiching it between OSB edges and 2x lumber? If this is an effective air sealing method, why use the tape at all? I don't mind extra sweat equity, if it saves me a bunch-o-money out of my wallet, yet is very effective.
I can get a case of 24 rolls of 2" 3M 8067 for $300 delivered. This will be all I need for the shop. I think one of the test articles mentioned using 3M 90 spray adhesive on the OSB first to get even better performance from the tape.
If 4" tape is the way to go, then the zip tape is more economical at 12 rolls of 90ft for $230, so so a case and some change will work better.
-Mike
GCP Ice and Water, cut up into 2" strips will cost $.15 a foot. I find it sticks very well on the smooth side of OSB. Vycor cut into 2" strips from 6" is a little less cost.
Joel, thank you for that excellent solution to minimize expenses. I assume you cut it with a razor knife and straight edge.
2” 3M 8067 off amazon comes in at $0.24 a ft and sticks very well to osb.
I second the 3M 8067 suggestion. 1.5" is plenty wide enough, so you could split 3" down the middle and cut costs by another 25%. Do NOT use aluminum tape. The slightest movement will tear it like tissue paper.
Ok, the backyard tape test demonstrated that 3M was awesome with OSB. I found a case of 24 rolls for about $290 and that is 1800 Lin feet of tape.
What about the OSB to treated lumber or or concrete? Do I put a sealer of some sort on the concrete where it will give a smooth surface to adhere?
I called and asked 3M tech support if spraying 3M 90 adhesive spray was advisable. They said it really did not serve any purpose. I made the call because someone had experienced increased adhesion in their experience. They said it works on concrte also, I just don't know how well? I don't want my great efforts at air sealing to deteriorate in a year.
I really appreciate all the great advice.
I also will tape the 2" Polyiso, unless it is senseless. I thought it might be better to leave a small gap and use spray foam as someone recommended, but I gut to wondering about some reading that mentioned expansion/contraction breaking the seal. The Polyiso will be exterior of the OSB and housewrap. It appears that most any tape will do the trick here, so I will plan to use housewrap tape here and I know I can get it for $0.05 per ft or maybe less.
The 8067 tape sticks well to concrete, as long as it is troweled relatively smooth (think a garage floor as opposed to a sidewalk). I can't think of a reason to use spray foam rather than tape at the seams of the polyiso.
Thanks Trevor.
Although I called and spoke with a techy at 3M about using 3M 90 Spray adhesive as a primer on OSB and they said no need. I found the reference material where it recommends it when needed. Also, the reference that states it works on concrete. Sounds like it would be a very cheap insurance.